“Niramisa domanassa” arises in a person who is on the mundane or Noble Path and is not making progress fast enough for them.
– For example, a Sotapanna may be worried about not making enough progress toward the Anagami stage. It is not depression. Just being anxious to get there faster.
P.S. I revised the post “Peace of Mind to Nibbāna – The Key Step” that Dipobhasaddhamma linked above. It is an old post I wrote in 2016.
– By the way, please copy the exact title of the post when you post a link.